Charger pulling more energy than the app states?

[Ngkgb]

I’ve consistently seen a discrepancy between how much energy my ChargePoint app says is going into the truck compared with what the Rivian app says. Last night the Rivian app says 82.3 kWh and the ChargePoint app says 85.9. Not a huge deal but am curious about why there would be a discrepancy.

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[SANZC02]

I’ve consistently seen a discrepancy between how much energy my ChargePoint app says is going into the truck compared with what the Rivian app says. Last night the Rivian app says 82.3 kWh and the ChargePoint app says 85.9. Not a huge deal but am curious about why there would be a discrepancy.

Are you just looking at what was added to the truck on the Rivian app? Inside the vehicle there is a session summary that breaks down how much energy went to other aspects like accessories. I do not think that number is part of the display in the app charge history. There also is a small amount of loss due to efficiency loss between what the charger sends and what the vehicle accepts.

 

[pickupman2022]

You will always see larger number on your charger (even more so on a DC fast charger). The charger will report total energy that when though it but that doesn't mean it all went to charing the battery. Your truck may have used some for other systems and there is what is known as charging losses. These are things like resistance of the charging cable, connections and heat.

 

[Ngkgb]

You will always see larger number on your charger (even more so on a DC fast charger). The charger will report total energy that when though it but that doesn't mean it all went to charing the battery. Your truck may have used some for other systems and there is what is known as charging losses. These are things like resistance of the charging cable, connections and heat.

So the number shown in the Rivian app is just the amount of energy that’s gone into the battery? That makes sense.

 

[BigSkies]

So the number shown in the Rivian app is just the amount of energy that’s gone into the battery? That makes sense.

A rule of thumb I've heard is ~10% of electricity coming from the wall is lost to either heat or to the AC to DC conversion.

 

[DucRider]

A rule of thumb I've heard is ~10% of electricity coming from the wall is lost to either heat or to the AC to DC conversion.

Taken a step further - the EPA efficiency testing (MPGe) is always measured "from the wall" and not energy used while operating the vehicle.
AC charging losses do average about 10% - they seem to be 8% to 12% (with a few outliers) when looking at the raw EPA test data for various manufacturers.

 

[KenCar]

When I charge at full amperage at home on my Tesla charger, the Tesla app will show about 0.5kWh more output than my Rivian App says is input. When I reduce the amperage by half, via the Rivian app, the output and input are equal. I presume most of the lost power is due to heat generated by the higher amperage. Low and slow is the way to go.

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